Method for fabricating semiconductor device with capacitors having shared electrode

ABSTRACT

The present application discloses a method for fabricating a semiconductor device with capacitors having a shared electrode. The method includes providing a substrate, forming a first trench in the substrate, doping sidewalls and a bottom surface of the first trench to form a bottom conductive structure, forming a first insulating layer on the bottom conductive structure and in the first trench, forming a shared conductive layer on the first insulating layer, forming a second insulating layer on the shared conductive layer, forming a top conductive layer on the second insulating layer, and forming a connection structure electrically connecting the bottom conductive structure and the top conductive layer. The bottom conductive structure, the first insulating layer, and the shared conductive layer together configure a first capacitor unit. The shared conductive layer, the second insulating layer, and the top conductive layer together configure a second capacitor unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. Non-Provisionalapplication Ser. No. 17/119,771 filed Dec. 11, 2020, which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a method for fabricating asemiconductor device, and more particularly, to a method for fabricatinga semiconductor device with capacitors having a shared electrode.

DISCUSSION OF THE BACKGROUND

Semiconductor devices are used in a variety of electronic applications,such as personal computers, cellular telephones, digital cameras, andother electronic equipment. The dimensions of semiconductor devices arecontinuously being scaled down to meet the increasing demand ofcomputing ability. However, a variety of issues arise during thescaling-down process, and such issues are continuously increasing.Therefore, challenges remain in achieving improved quality, yield,performance, and reliability and reduced complexity.

This Discussion of the Background section is provided for backgroundinformation only. The statements in this Discussion of the Backgroundare not an admission that the subject matter disclosed in this sectionconstitutes prior art to the present disclosure, and no part of thisDiscussion of the Background section may be used as an admission thatany part of this application, including this Discussion of theBackground section, constitutes prior art to the present disclosure.

SUMMARY

One aspect of the present disclosure provides a semiconductor deviceincluding a substrate, a first capacitor unit, a second capacitor unit,and a connection structure. The first capacitor unit includes a bottomconductive structure inwardly positioned in the substrate, and a sharedconductive layer positioned above the bottom conductive structure with afirst insulating layer interposed therebetween. The second capacitorunit includes the shared conductive layer, a top conductive layerpositioned above the shared conductive layer with a second insulatinglayer interposed therebetween. The connection structure electricallyconnects the bottom conductive structure and the top conductive layersuch that the first capacitor unit and the second capacitor unit are inparallel.

In some embodiments, a width of the second insulating layer is greaterthan a width of the shared conductive layer.

In some embodiments, the semiconductor device includes first spacerspositioned on sidewalls of the shared conductive layer.

In some embodiments, the connection structure including a firstconductive via electrically connecting the top conductive layer, asecond conductive via electrically connecting the bottom conductivestructure, and a conductive line horizontally positioned on the firstconductive via and the second conductive via and electrically connectthe first conductive via and the second conductive via.

In some embodiments, the semiconductor device includes an assistantconductive layer positioned between the second conductive via and thebottom conductive structure. The assistant conductive layer is formed oftitanium silicide, nickel silicide, nickel platinum silicide, tantalumsilicide, or cobalt silicide.

In some embodiments, a thickness of the assistant conductive layer isbetween about 2 nm and about 20 nm.

In some embodiments, the first insulating layer is anoxide-nitride-oxide structure.

In some embodiments, the first insulating layer is formed of aninsulating material having a dielectric constant of about 4.0 orgreater.

In some embodiments, the semiconductor device includes an interfaciallayer positioned between the bottom conductive structure and the firstinsulating layer. The interfacial layer is formed of silicon oxide.

In some embodiments, a thickness of the interfacial layer is betweenabout 7 angstroms and about 12 angstroms.

In some embodiments, the semiconductor device includes a first barrierlayer positioned between the first insulating layer and the sharedconductive layer. The first barrier layer is formed of titanium,titanium nitride, titanium silicon nitride, tantalum, tantalum nitride,tantalum silicon nitride, or a combination thereof.

In some embodiments, a thickness of the first barrier layer is betweenabout 10 angstroms and about 15 angstroms.

In some embodiments, a thickness of the first insulating layer is about10 angstroms and about 1000 angstroms.

In some embodiments, a width of the top conductive layer is less thanthe width of the shared conductive layer.

In some embodiments, the shared conductive layer includes a connectionportion positioned above a top surface of the substrate and a bottomportion extending downwardly to the substrate.

Another aspect of the present disclosure provides a method forfabricating a semiconductor device including providing a substrate,forming a first trench in the substrate, doping sidewalls and a bottomsurface of the first trench to form a bottom conductive structure,forming a first insulating layer on the bottom conductive structure andin the first trench, forming a shared conductive layer on the firstinsulating layer, forming a second insulating layer on the sharedconductive layer, forming a top conductive layer on the secondinsulating layer, and forming a connection structure electricallyconnecting the bottom conductive structure and the top conductive layer.The bottom conductive structure, the first insulating layer, and theshared conductive layer together configure a first capacitor unit. Theshared conductive layer, the second insulating layer, and the topconductive layer together configure a second capacitor unit.

In some embodiments, the substrate and the bottom conductive structurehave opposite electrical type.

In some embodiments, an aspect ratio of the first trench is betweenabout 1:6 and about 1:20.

In some embodiments, the first insulating layer is formed of aninsulating material having a dielectric constant of about 4.0 orgreater.

In some embodiments, the method for fabricating the semiconductor deviceincludes a step of forming first spacers on sidewalls of the sharedconductive layer before the step of forming the second insulating layeron the shared conductive layer.

Due to the design of the semiconductor device of the present disclosure,the capacitance density may be increased by the stacked and electricallyparalleled coupled first capacitor unit and second capacitor unit.Accordingly, the effective capacitance of the semiconductor device maybe increased such that the performance of the semiconductor device maybe improved.

The foregoing has outlined rather broadly the features and technicaladvantages of the present disclosure in order that the detaileddescription of the disclosure that follows may be better understood.Additional features and advantages of the disclosure will be describedhereinafter, and form the subject of the claims of the disclosure. Itshould be appreciated by those skilled in the art that the conceptionand specific embodiment disclosed may be readily utilized as a basis formodifying or designing other structures or processes for carrying outthe same purposes of the present disclosure. It should also be realizedby those skilled in the art that such equivalent constructions do notdepart from the spirit and scope of the disclosure as set forth in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It shouldbe noted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates, in a flowchart diagram form, a method forfabricating a semiconductor device in accordance with one embodiment ofthe present disclosure;

FIGS. 2 to 12 illustrate, in schematic cross-sectional view diagrams, aflow for fabricating the semiconductor device in accordance with oneembodiment of the present disclosure;

FIG. 13 illustrates, in a schematic circuit diagram, the semiconductordevice in accordance with one embodiment of the present disclosure;

FIGS. 14 and 15 illustrate, in schematic cross-sectional view diagrams,part a flow for fabricating a semiconductor device in accordance withanother embodiment of the present disclosure;

FIGS. 16 to 19 illustrate, in schematic cross-sectional view diagrams,semiconductor devices in accordance with some embodiments of the presentdisclosure;

FIGS. 20 and 21 illustrate, in schematic cross-sectional view diagrams,part a flow for fabricating a semiconductor device in accordance withanother embodiment of the present disclosure;

FIGS. 22 to 24 illustrate, in schematic cross-sectional view diagrams,part a flow for fabricating a semiconductor device in accordance withanother embodiment of the present disclosure;

FIGS. 25 to 29 illustrate, in schematic cross-sectional view diagrams,part a flow for fabricating a semiconductor device in accordance withanother embodiment of the present disclosure;

FIGS. 30 to 33 illustrate, in schematic cross-sectional view diagrams,part a flow for fabricating a semiconductor device in accordance withanother embodiment of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

It should be understood that when an element or layer is referred to asbeing “connected to” or “coupled to” another element or layer, it can bedirectly connected to or coupled to another element or layer, orintervening elements or layers may be present.

It should be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. Unless indicated otherwise, these terms areonly used to distinguish one element from another element. Thus, forexample, a first element, a first component or a first section discussedbelow could be termed a second element, a second component or a secondsection without departing from the teachings of the present disclosure.

Unless the context indicates otherwise, terms such as “same,” “equal,”“planar,” or “coplanar,” as used herein when referring to orientation,layout, location, shapes, sizes, amounts, or other measures do notnecessarily mean an exactly identical orientation, layout, location,shape, size, amount, or other measure, but are intended to encompassnearly identical orientation, layout, location, shapes, sizes, amounts,or other measures within acceptable variations that may occur, forexample, due to manufacturing processes. The term “substantially” may beused herein to reflect this meaning. For example, items described as“substantially the same,” “substantially equal,” or “substantiallyplanar,” may be exactly the same, equal, or planar, or may be the same,equal, or planar within acceptable variations that may occur, forexample, due to manufacturing processes.

In the present disclosure, a semiconductor device generally means adevice which can function by utilizing semiconductor characteristics,and an electro-optic device, a light-emitting display device, asemiconductor circuit, and an electronic device are all included in thecategory of the semiconductor device.

It should be noted that, in the description of the present disclosure,above (or up) corresponds to the direction of the arrow of the directionZ, and below (or down) corresponds to the opposite direction of thearrow of the direction Z.

FIG. 1 illustrates, in a flowchart diagram form, a method 10 forfabricating a semiconductor device 1A in accordance with one embodimentof the present disclosure. FIGS. 2 to 12 illustrate, in schematiccross-sectional view diagrams, a flow for fabricating the semiconductordevice 1A in accordance with one embodiment of the present disclosure.FIG. 13 illustrates, in a schematic circuit diagram, the semiconductordevice 1A in accordance with one embodiment of the present disclosure.

With reference to FIGS. 1 to 4 , at step S11, a substrate 101 may beprovided, first trenches 701 may be formed in the substrate 101, and abottom conductive structure 200 may be formed in the substrate 101.

With reference to FIG. 2 , the substrate 101 may be a bulk semiconductorsubstrate. The bulk semiconductor substrate may be formed of, forexample, an elementary semiconductor such as silicon or germanium or acompound semiconductor such as silicon germanium, silicon carbide,gallium arsenide, gallium phosphide, indium phosphide, indium arsenide,indium antimonide, or other III-V compound semiconductor or II-VIcompound semiconductor.

In some embodiments, the substrate 101 may include asemiconductor-on-insulator structure which is consisted of, from bottomto top, a handle substrate, an insulator layer, and a topmostsemiconductor material layer. The handle substrate and the topmostsemiconductor material layer may be formed of a same material as thebulk semiconductor substrate aforementioned. The insulator layer may bea crystalline or non-crystalline dielectric material such as an oxideand/or nitride. For example, the insulator layer may be a dielectricoxide such as silicon oxide. For another example, the insulator layermay be a dielectric nitride such as silicon nitride or boron nitride.For yet another example, the insulator layer may include a stack of adielectric oxide and a dielectric nitride such as a stack of, in anyorder, silicon oxide and silicon nitride or boron nitride. The insulatorlayer may have a thickness between about 10 nm and about 200 nm.

In some embodiments, the substrate 101 may be doped with a dopant suchas phosphorus, arsenic, antimony, or boron and may have a firstelectrical type. The substrate 101 may have a first dopantconcentration.

With reference to FIG. 2 , a first hard mask layer 601 may be formed onthe substrate 101. The first hard mask layer 601 may be formed of, forexample, silicon oxide, silicon nitride, silicon oxynitride, siliconnitride oxide, boron nitride, silicon boron nitride, phosphorus boronnitride, or boron carbon silicon nitride. The first hard mask layer 601may include a pattern of the first trenches 701.

It should be noted that, in the present disclosure, silicon oxynitriderefers to a substance which contains silicon, nitrogen, and oxygen andin which a proportion of oxygen is greater than that of nitrogen.Silicon nitride oxide refers to a substance which contains silicon,oxygen, and nitrogen and in which a proportion of nitrogen is greaterthan that of oxygen.

With reference to FIG. 2 , an etch process, such as an anisotropic dryetch process, may be performed to remove portions of the substrate 101and concurrently form the first trenches 701. The first trenches 701 mayextend downwardly from a top surface 101TS of the top surface 101TS. Apillar portion 101P of the substrate 101 may be formed between anadjacent pair of the first trenches 701. Each of the first trenches 701may include two sidewalls 701S and a bottom surfaces 701B. In someembodiments, an aspect ratio of the first trenches 701 may be betweenabout 1:6 and about 1:20. In some embodiments, the bottom surfaces 701Bof the first trenches 701 may be rounded.

It should be noted that only two first trenches 701 are shown in FIG. 2for clarity. The number of first trenches 701 can be more than one.

It should be noted that, in the description of the present disclosure, asurface of an element (or a feature) located at the highest verticallevel along the direction Z is referred to as a top surface of theelement (or the feature). A surface of an element (or a feature) locatedat the lowest vertical level along the direction Z is referred to as abottom surface of the element (or the feature).

With reference to FIG. 3 , a first mask layer 603 may be formed on thefirst hard mask layer 601. The first mask layer 603 may be a photoresistlayer and may have a pattern of the bottom conductive structure 200.Some portions of the first hard mask layer 601 may be exposed throughthe pattern of the first mask layer 603. For example, the portion of thefirst hard mask layer 601 on the pillar portion 101P of the substrate101 may not be covered by the first mask layer 603. Subsequently, anetch process, such as wet etch process, may be performed to remove theexposed portions of the first hard mask layer 601. The etch rate ratioof the first hard mask layer 601 to the substrate 101 may be betweenabout 100:1 and about 1.05:1, between about 15:1 and about 2:1, orbetween about 10:1 and about 2:1 during the etch process. After the etchprocess, the first mask layer 603 may be removed.

With reference to FIG. 4 , an implantation process may be performed todope regions of the substrate 101 and turn these regions of thesubstrate 101 into the bottom conductive structure 200. In someembodiments, the regions adjacent to the exposed top surface 101TS ofsubstrate 101 and the regions adjacent to the sidewalls 701S and thebottom surfaces 701B of the first trenches 701 may be turned into thebottom conductive structure 200. That is, the bottom conductivestructure 200 may have a geometry that follows the contours of the firsttrenches 701. The dopant of the implantation process may be, forexample, phosphorus, arsenic, antimony, or boron. The bottom conductivestructure 200 may include a second electrical type opposite to the firstelectrical type. The bottom conductive structure 200 may have a seconddopant concentration greater than the first dopant concentration of thesubstrate 101.

With reference to FIG. 4 , the bottom conductive structure 200 mayinclude flat portions 200F and concave portions 200C-1, 200C-3. The flatportions 200F of the bottom conductive structure 200 may be formedadjacent to the exposed top surface 101TS of substrate 101. The concaveportions 200C-1, 200C-3 of the bottom conductive structure 200 may beformed adjacent to the sidewalls 701S and the bottom surfaces 701B ofthe first trenches 701. It should be noted that the pillar portion 101Plocated between the concave portions 200C-1, 200C-3 of the bottomconductive structure 200 may still undoped. The geometry of the pillarportion 101P may provide provides an increased amount of area for afirst capacitor unit CAP1 which will be illustrated later. As a result,the presence of the pillar portion 101P may provide an increasedcapacitance of the semiconductor device 1A.

With reference to FIGS. 1 and 5 , at step S13, a first insulating layer301 may be conformally formed on the substrate 101 and in the firsttrenches 701.

With reference to FIG. 5 , the first insulating layer 301 may beconformally formed on the top surface 101TS of the substrate 101, on thesidewalls 701S of the first trenches 701, and on the bottom surfaces701B of the first trenches 701. The first insulating layer 301 mayelectrically isolate the bottom conductive structure 200 from conductivefeatures, which will be fabricated later, above the first insulatinglayer 301. The first insulating layer 301 may include flat portion 301Fand concave portions 301C-1, 301C-3. The flat portion 301F may be formedon the top surface 101TS of the substrate 101. The concave portions301C-1, 301C-3 may be formed on the sidewalls 701S and bottom surfaces701B of the first trenches 701. In some embodiments, the firstinsulating layer 301 may have a thickness T1 between about 10 angstromsand about 1000 angstroms. In some embodiments, the first insulatinglayer 301 may be formed by low pressure chemical vapor deposition,plasma-enhanced chemical vapor deposition, atomic layer deposition, orthe like.

In some embodiments, the first insulating layer 301 may be a stackedlayer structure such as an oxide-nitride-oxide structure. In someembodiments, the first insulating layer 301 may be formed of, forexample, silicon oxide, silicon nitride, silicon oxynitride, siliconnitride oxide, or the like.

In some embodiments, the first insulating layer 301 may be formed of,for example, a high-k dielectric material such as metal oxide, metalnitride, metal silicate, transition metal-oxide, transitionmetal-nitride, transition metal-silicate, oxynitride of metal, metalaluminate, zirconium silicate, zirconium aluminate, or a combinationthereof. In some embodiments, the first insulating layer 301 may beformed of hafnium oxide, hafnium silicon oxide, hafnium siliconoxynitride, hafnium tantalum oxide, hafnium titanium oxide, hafniumzirconium oxide, hafnium lanthanum oxide, lanthanum oxide, zirconiumoxide, titanium oxide, tantalum oxide, yttrium oxide, strontium titaniumoxide, barium titanium oxide, barium zirconium oxide, lanthanum siliconoxide, aluminum silicon oxide, aluminum oxide, silicon nitride, siliconoxynitride, silicon nitride oxide, or a combination thereof. In someembodiments, the first insulating layer 301 may be a stacked layerstructure that includes, for example, one layer of silicon oxide andanother layer of high-k dielectric material.

It should be noted that, a “thickness” refers to a vertical size of anelement (e.g., a layer, trench, hole, opening, etc.) in thecross-sectional views measured from a top surface to a bottom surface ofthe element.

With reference to FIGS. 1, 6 and 7 , at step S15, a shared conductivelayer 303 may be formed on the first insulating layer 301.

With reference to FIG. 6 , a layer of first conductive material 605 maybe formed to fill the first trenches 701 and cover the first insulatinglayer 301. A planarization process, such as chemical mechanicalpolishing, may be performed to provide a substantially flat surface forsubsequent processing steps.

In some embodiments, the first conductive material 605 may be, forexample, polycrystalline silicon, doped polycrystalline silicon,polycrystalline silicon germanium, doped polycrystalline silicongermanium, aluminum, copper, platinum, gold, titanium, titanium nitride,tantalum, tantalum nitride, tungsten, tungsten nitride, or alloy of goldand copper.

In some embodiments, the first conductive material 605 may be, forexample, a material from the class containing metal borides, metalphosphides, and metal antimonide of the transition metals from thesecondary groups IV, V and VI of the periodic table. The transitionmetals may be titanium, zirconium, hafnium, vanadium, niobium, tantalum,chromium, molybdenum, or tungsten. In some embodiments, the material maybe titanium diboride, zirconium diboride, hafnium diboride, titaniumphosphide, zirconium phosphide, hafnium phosphide, titanium antimonide,zirconium antimonide, or hafnium antimonide. The aforementioned materialmay have a high thermal stability and excellent conductivity whichspecific resistance may be less than 20 micro Ohm-cm.

With reference to FIG. 6 , a second mask layer 607 may be formed on thelayer of first conductive material 605. The second mask layer 607 may bea photoresist layer and may have a pattern of the shared conductivelayer 303.

With reference to FIG. 7 , an etch process, such as an anisotropic dryetch process, may be performed to remove portions of the layer of firstconductive material 605 and portions of the first insulating layer 301.After the etch process, the layer of first conductive material 605 maybe turned into the shared conductive layer 303 and the first insulatinglayer 301 may be trimmed. A portion of the flat portions 200F of thebottom conductive structure 200 may be exposed. After the etch process,the second mask layer 607 may be removed.

With reference to FIG. 7 , the shared conductive layer 303 may include aconnection portion 303C and bottom portions 303B. The connection portion303C of the shared conductive layer 303 may be horizontally above thetop surface 101TS of the substrate 101 and on the flat portion 301F ofthe first insulating layer 301. The connection portion 303C of theshared conductive layer 303 may have a thickness T2 between about 50angstroms and about 1000 angstroms. The bottom portions 303B of theshared conductive layer 303 may downwardly extend from the connectionportion 303C of the shared conductive layer 303 and toward to thesubstrate 101. The concave portions 301C-1, 301C-3 of the firstinsulating layer 301 may surround the bottom portions 303B of the sharedconductive layer 303.

It should be noted that “an element A surrounds an element B” (orsimilar language) as used herein means that the element A is at leastpartially around the element B but does not necessarily mean that theelement A completely encloses the element B.

With reference to FIG. 7 , the bottom conductive structure 200, thefirst insulating layer 301, and the shared conductive layer 303 togetherconfigure the first capacitor unit CAP1.

With reference to FIGS. 1, 8, and 9 , at step S17, first spacers 401 maybe formed on sidewalls 303S of the shared conductive layer 303.

With reference to FIG. 8 , a layer of first insulating material 609 maybe formed to cover the top surface 101TS of the substrate 101, thesidewalls of the first insulating layer 301, the sidewalls 303S and thetop surface of the shared conductive layer 303. In some embodiments, thefirst spacers 401 may have a thickness T3 between about 1 nm and about 3nm. In some embodiments, the first insulating material 609 may be forexample, a semiconductor oxide, a semiconductor nitride, a semiconductorcarbide, a semiconductor oxynitride, or a combination thereof.

With reference to FIG. 9 , an etch process, such as an anisotropic dryetch process, may be performed to remove portions of the layer of firstinsulating material 609 and concurrently turn the layer of firstinsulating material 609 into the first spacers 401. The first spacers401 may provide additional electrical isolation to the shared conductivelayer 303 in the horizontal direction.

With reference to FIGS. 1 and 10 , at step S19, a second insulatinglayer 305 may be conformally formed on the shared conductive layer 303.

With reference to FIG. 10 , the second insulating layer 305 may beformed to cover the top surface 101TS of the substrate 101, the firstspacers 401, and the shared conductive layer 303. A width W2 of thesecond insulating layer 305 may be greater than a width W1 of the sharedconductive layer 303. The second insulating layer 305 may be formed of asame material as the first insulating layer 301 but is not limitedthereto. The second insulating layer 305 may electrically isolate theshared conductive layer 303 from conductive features, which will befabricated later, above the second insulating layer 305.

It should be noted that, a “width” refers to a size of an element (e.g.,a layer, trench, hole, opening, etc.) in the drawings measured from aside surface to an opposite surface of the element. The term “thickness”may substitute for “width” where indicated.

With reference to FIGS. 1 and 11 , at step S21, a top conductive layer307 may be formed on the second insulating layer 305.

With reference to FIG. 11 , an inter-layer dielectric 403-1 may beformed to cover the second insulating layer 305. A planarizationprocess, such as chemical mechanical polishing, may be performed untilthe top surface 305TS of the second insulating layer 305 is exposed toremove excess material and provide a substantially flat surface forsubsequent processing steps. An inter-layer dielectric 403-3 may besequentially formed on the inter-layer dielectric 403-1. The inter-layerdielectrics 403-1, 403-3 may be formed of a low-k dielectric materialsuch as phosphosilicate glass, borophosphosilicate glass, fluorinatedsilicate glass, spin-on-glass, spin-on-polymers, silicon carbonmaterial, or a combination thereof. The inter-layer dielectrics 403-1,403-3 may act as an insulator that supports and isolates the topconductive layer 307 as will be illustrated later.

With reference to FIG. 11 , the top conductive layer 307 may be formedon the second insulating layer 305 and in the inter-layer dielectric403-3. A width W3 of the top conductive layer 307 may be less than awidth W1 of the shared conductive layer 303. In some embodiments, thetop conductive layer 307 may be formed of, for example, polycrystallinesilicon, doped polycrystalline silicon, polycrystalline silicongermanium, doped polycrystalline silicon germanium, aluminum, copper,platinum, gold, titanium, titanium nitride, tantalum, tantalum nitride,tungsten, tungsten nitride, or alloy of gold and copper. For example,the top conductive layer 307 may be formed of copper and may be formedby a damascene process. In some embodiments, the top conductive layer307 may be formed of a same material as the shared conductive layer 303.

With reference to FIG. 11 , the shared conductive layer 303, the secondinsulating layer 305, and the top conductive layer 307 togetherconfigure a second capacitor unit CAP2.

With reference to FIGS. 1 and 12 , at step S23, a connection structure500 may be formed to electrically couple the bottom conductive structure200 and the top conductive layer 307.

With reference to FIG. 12 , the connection structure 500 may includeconductive lines 501-1, 501-3 and conductive vias 503-1, 503-3, 503-5,503-7. The conductive lines 501-1, 501-3 may be formed above theinter-layer dielectric 403-3 and may be horizontally disposed. Theconductive via 503-1 may be formed electrically connecting theconductive line 501-1 and the shared conductive layer 303. Theconductive via 503-3 may be formed electrically connecting theconductive line 501-3 and the top conductive layer 307. The conductivevia 503-5 may be formed electrically connecting the conductive line501-3 and the bottom conductive structure 200. The conductive via 503-7may be formed on the conductive line 501-3.

In some embodiments, the conductive lines 501-1, 501-3 and theconductive vias 503-1, 503-3, 503-5, 503-7 may be formed of, forexample, conductive metal nitride (e.g., titanium nitride or tantalumnitride) or metal (e.g., titanium, tantalum, tungsten, copper, oraluminum).

It should be noted that the inter-layer dielectric which supports andisolates the conductive lines 501-1, 501-3 and the conductive vias503-1, 503-3, 503-5, 503-7 may be omitted in FIG. 12 for clarity.

With reference to FIGS. 12 and 13 , the first capacitor unit CAP1 andthe second capacitor unit CAP2 may be stacked together and may beelectrically coupled in parallel by the connection structure 500 toincrease the capacitance density. Accordingly, the effective capacitanceof the semiconductor device 1A may be increased. As a result, theperformance of the semiconductor device 1A may be improved.

FIGS. 14 and 15 illustrate, in schematic cross-sectional view diagrams,part a flow for fabricating a semiconductor device 1B in accordance withanother embodiment of the present disclosure.

With reference to FIG. 14 , an intermediate semiconductor device may befabricating with a procedure similar to that illustrated in FIGS. 2 to 7. The inter-layer dielectric 403-1 may be formed to cover the topsurface 101TS of the substrate 101, the first insulating layer 301, andthe shared conductive layer 303. A planarization process, such aschemical mechanical polishing, may be performed until the top surface303TS of the shared conductive layer 303 is exposed to provide asubstantially flat surface for subsequent processing steps.Subsequently, the second insulating layer 305 may be formed on theshared conductive layer 303 and on the inter-layer dielectric 403-1. Thewidth W2 of the second insulating layer 305 may be greater than thewidth W1 of the shared conductive layer 303.

With reference to FIG. 15 , the inter-layer dielectric 403-3, the topconductive layer 307, and the connection structure 500 may be formedwith a procedure similar to that illustrated in FIGS. 11 and 12 .

FIGS. 16 to 19 illustrate, in schematic cross-sectional view diagrams,semiconductor devices 1C, 1D, 1E, and 1F in accordance with someembodiments of the present disclosure.

With reference to FIG. 16 , the semiconductor device 1C may have astructure similar to that illustrated in FIG. 15 . The same or similarelements in FIG. 16 as in FIG. 15 have been marked with similarreference numbers and duplicative descriptions have been omitted. Thewidth W2 of the second insulating layer 305 may be less than the widthW1 of the shared conductive layer 303.

With reference to FIG. 17 , the semiconductor device 1D may have astructure similar to that illustrated in FIG. 12 . The same or similarelements in FIG. 17 as in FIG. 12 have been marked with similarreference numbers and duplicative descriptions have been omitted.

With reference to FIG. 17 , the semiconductor device 1D may include afirst barrier layer 405 and a second barrier layer 407. The firstbarrier layer 405 may be disposed between the first insulating layer 301and the shared conductive layer 303. The second barrier layer 407 may bedisposed between the second insulating layer 305 and the top conductivelayer 307. The first barrier layer 405 and the second barrier layer 407may have thicknesses between about 10 angstroms and about 15 angstromsor between about 11 angstroms and about 13 angstroms. The first barrierlayer 405 and the second barrier layer 407 may be formed of, forexample, titanium, titanium nitride, titanium silicon nitride, tantalum,tantalum nitride, tantalum silicon nitride, or combination thereof. Thefirst barrier layer 405 may improve the adhesion between the firstinsulating layer 301 and the shared conductive layer 303. The secondbarrier layer 407 may improve the adhesion between the second insulatinglayer 305 and the top conductive layer 307.

With reference to FIG. 18 , the semiconductor device 1E may have astructure similar to that illustrated in FIG. 12 . The same or similarelements in FIG. 18 as in FIG. 12 have been marked with similarreference numbers and duplicative descriptions have been omitted.

With reference to FIG. 18 , the semiconductor device 1E may include aninterfacial layer 409. The interfacial layer 409 may be disposed betweenthe first insulating layer 301 and the bottom conductive structure 200.The interfacial layer 409 may have a thickness between about 7 angstromsand 12 angstroms or between about 8 angstroms and 10 angstroms. Theinterfacial layer 409 may facilitate the formation of the firstinsulating layer 301 during fabrication of the semiconductor device 1E.

With reference to FIG. 19 , the semiconductor device 1F may have astructure similar to that illustrated in FIG. 12 . The same or similarelements in FIG. 19 as in FIG. 12 have been marked with similarreference numbers and duplicative descriptions have been omitted.

With reference to FIG. 19 , the semiconductor device 1F may include anassistant conductive layer 411. The assistant conductive layer 411 maybe disposed between the conductive via 503-5 and the flat portions 200Fof the bottom conductive structure 200. The assistant conductive layer411 may have a thickness between about 2 nm and about 20 nm. Theassistant conductive layer 411 may be formed of, for example, titaniumsilicide, nickel silicide, nickel platinum silicide, tantalum silicide,or cobalt silicide. The assistant conductive layer 411 may reduce thecontact resistance between the conductive via 503-5 and the flatportions 200F of the bottom conductive structure 200.

FIGS. 20 and 21 illustrate, in schematic cross-sectional view diagrams,part a flow for fabricating a semiconductor device 1G in accordance withanother embodiment of the present disclosure.

With reference to FIG. 20 , the substrate 101 and the first trenches 701may be formed with a procedure similar to that illustrated in FIG. 2 . Abottom conductive structure 200′ may be conformally formed in the firsttrenches 701 and on the top surface 101TS of the substrate 101. Thebottom conductive structure 200′ may include flat portions 200′F andconcave portions 200′C-1, 200′C-3. The flat portions 200′F may be formedon the top surface 101TS of the substrate 101. The concave portions200′C-1, 200′C-3 may be formed on the sidewalls 701S and the bottomsurfaces 701B of the first trenches 701. The bottom conductive structure200′ may have a thickness T5 between about 50 angstroms and about 1000angstroms.

The bottom conductive structure 200′ may be formed by a depositionprocess. In some embodiments, an etch process may be subsequentlyperformed after the deposition process to trim the bottom conductivestructure 200′. The deposition process may be chemical vapor deposition,plasma-enhanced chemical vapor deposition, physical vapor deposition,atomic layer deposition, or the like. The bottom conductive structure200′ may be formed of, for example, polycrystalline silicon, dopedpolycrystalline silicon, polycrystalline silicon germanium, dopedpolycrystalline silicon germanium, aluminum, copper, platinum, gold,titanium, titanium nitride, tantalum, tantalum nitride, tungsten,tungsten nitride, or alloy of gold and copper.

With reference to FIG. 21 , the first insulating layer 301 may beconformally formed on the top surface 101TS of the substrate 101 and onthe bottom conductive structure 200′. In some embodiments, the flatportion 301F of the first insulating layer 301 may be formed on the topsurface 101TS of the substrate 101 and on the flat portions 200′F of thebottom conductive structure 200′. The concave portions 301C-1, 301C-3 ofthe first insulating layer 301 may be formed on the concave portions200′C-1, 200′C-3 of the bottom conductive structure 200′ and in thefirst trenches 701. The shared conductive layer 303, the secondinsulating layer 305, the top conductive layer 307, the inter-layerdielectrics 403-1, 403-3, and the connection structure 500 may be formedwith a procedure similar to that illustrated in FIGS. 14 and 15 .

With reference to FIG. 21 , the bottom conductive structure 200′, thefirst insulating layer 301, and the shared conductive layer 303 togetherconfigure the first capacitor unit CAP1. The shared conductive layer303, the second insulating layer 305, and the top conductive layer 307together configure the second capacitor unit CAP2. The first capacitorunit CAP1 and the second capacitor unit CAP2 may be electrical parallelby the connection structure 500.

FIGS. 22 to 24 illustrate, in schematic cross-sectional view diagrams,part a flow for fabricating a semiconductor device 1H in accordance withanother embodiment of the present disclosure.

With reference to FIG. 22 , an impurity region 103 may be formed in thesubstrate 101. In some embodiments, the impurity region 103 may beformed by providing a mask (not shown) over the substrate 101 anddirecting a beam of ions toward the masked substrate 101. The mask mayblock ions or diffusion species from entering the substrate 101, whereasions or diffusion species pass through an opening in the mask to formthe impurity region 103. In some embodiments, the impurity region 103may be formed using a phosphorous oxychloride doping method or someother doping method, rather than ion implantation. The impurity region103 may have the second electrical type opposite to the first electricaltype of the substrate 101. In some embodiments, the dopant concentrationof the impurity region 103 may be between about 1E19 atoms/cm³ and about1E21 atoms/cm³.

With reference to FIG. 23 , the first hard mask layer 601 may be formedon the substrate 101 and may have the pattern of the first trenches 701.An etch process, such as an anisotropic dry etch process, may beperformed to remove portions of the substrate 101 and concurrently formthe first trenches 701. After the etch process, the impurity region 103may be turned into a bottom conductive structure 200″. The bottomconductive structure 200″ may surround the first trenches 701.

With reference to FIG. 24 , the first insulating layer 301, the sharedconductive layer 303, the second insulating layer 305, the topconductive layer 307, the inter-layer dielectrics 403-1, 403-3, and theconnection structure 500 may be formed with a procedure similar to thatillustrated in FIGS. 5 to 12 .

With reference to FIG. 24 , the bottom conductive structure 200″, thefirst insulating layer 301, and the shared conductive layer 303 togetherconfigure the first capacitor unit CAP1. The shared conductive layer303, the second insulating layer 305, and the top conductive layer 307together configure the second capacitor unit CAP2. The first capacitorunit CAP1 and the second capacitor unit CAP2 may be electrical parallelby the connection structure 500.

FIGS. 25 to 29 illustrate, in schematic cross-sectional view diagrams,part a flow for fabricating a semiconductor device 1I in accordance withanother embodiment of the present disclosure.

With reference to FIG. 25 , the substrate 101 and the first trenches 701may be formed with a procedure similar to that illustrated in FIG. 2 . Acovering layers 413 may be formed to cover the top surface 101TS of thesubstrate 101 and upper portions of the first trenches 701. In someembodiments, the covering layers 413 may be formed to cover the topsurface 101TS of the substrate 101 and upper portions of the sidewalls701S of the first trenches 701.

In some embodiments, the covering layers 413 may be formed of, forexample, aluminum oxide, hafnium oxide, zirconium oxide, titanium oxide,titanium nitride, tungsten nitride, silicon nitride, or silicon oxide.The covering layers 413 may be formed by a deposition process such as anatomic layer deposition method precisely controlling an amount of afirst precursor of the atomic layer deposition method.

In some embodiments, when the covering layers 413 are formed of aluminumoxide, the first precursor of the atomic layer deposition method may betrimethylaluminum and a second precursor of the atomic layer depositionmethod may be water or ozone.

In some embodiments, when the covering layers 413 are formed of hafniumoxide, the first precursor of the atomic layer deposition method may behafnium tetrachloride, hafnium tert-butoxide, hafnium dimethylamide,hafnium ethylmethylamide, hafnium diethylamide, or hafniummethoxy-t-butoxide and the second precursor of the atomic layerdeposition method may be water or ozone.

In some embodiments, when the covering layers 413 are formed ofzirconium oxide, the first precursor of the atomic layer depositionmethod may be zirconium tetrachloride and the second precursor of theatomic layer deposition method may be water or ozone.

In some embodiments, when the covering layers 413 are formed of titaniumoxide, the first precursor of the atomic layer deposition method may betitanium tetrachloride, tetraethyl titanate, or titanium isopropoxideand the second precursor of the atomic layer deposition method may bewater or ozone.

In some embodiments, when the covering layers 413 are formed of titaniumnitride, the first precursor of the atomic layer deposition method maybe titanium tetrachloride and ammonia.

In some embodiments, when the covering layers 413 are formed of tungstennitride, the first precursor of the atomic layer deposition method maybe tungsten hexafluoride and ammonia.

In some embodiments, when the covering layers 413 are formed of siliconnitride, the first precursor of the atomic layer deposition method maybe silylene, chlorine, ammonia, and/or dinitrogen tetrahydride.

In some embodiments, when the covering layers 413 are formed of siliconoxide, the first precursor of the atomic layer deposition method may besilicon tetraisocyanate or CH₃OSi(NCO)₃ and the second precursor of theatomic layer deposition method may be hydrogen or ozone.

With reference to FIG. 25 , a dopant source liner 611 may be conformallyformed to cover the covering layers 413 and the lower portions of thefirst trenches 701. The dopant source liner 611 may be formed of, forexample, arsenic silicate glass and may serve as a dopant source forforming bottom conductive structure 200′″ as will be illustrated later.

With reference to FIG. 26 , an annealing process may be performed todiffuse out the dopant source liner 611 and form the bottom conductivestructure 200′″ in regions surrounding the lower portions of the firsttrenches 701.

With reference to FIG. 27 , a wet etch process may be performed toremove the dopant source liner 611. The etch rate ratio of the dopantsource liner 611 to the covering layers 413 may be between about betweenabout 15:1 and about 2:1 or between about 10:1 and about 2:1 during thewet etch process. The etch rate ratio of the dopant source liner 611 tothe substrate 101 may be between about between about 15:1 and about 2:1or between about 10:1 and about 2:1 during the wet etch process.

With reference to FIG. 28 , the first insulating layer 301 may beconformally formed to cover the covering layers 413, the lower portionsof the sidewalls 701S of the first trenches 701, and the bottom surfaces701B of the first trenches 701.

With reference to FIG. 29 , the shared conductive layer 303 may beformed to fill the first trenches 701 and on the first insulating layer301. During the deposition of the shared conductive layer 303, thecovering layers 413 may reduce the deposition rate on the sidewalls 701Sof the first trenches 701 relative to the deposition rate on the bottomsurfaces 701B of the first trenches 701 such that the first trenches 701may be filled without any void formation near the bottom surfaces 701Bof the first trenches 701. The second insulating layer 305, the topconductive layer 307, the inter-layer dielectrics 403-1, 403-3, and theconnection structure 500 may be formed with a procedure similar to thatillustrated in FIGS. 14 and 15 .

With reference to FIG. 29 , the bottom conductive structure 200′″, thefirst insulating layer 301, and the shared conductive layer 303 togetherconfigure the first capacitor unit CAP1. The shared conductive layer303, the second insulating layer 305, and the top conductive layer 307together configure the second capacitor unit CAP2. The first capacitorunit CAP1 and the second capacitor unit CAP2 may be electrical parallelby the connection structure 500.

FIGS. 30 to 33 illustrate, in schematic cross-sectional view diagrams,part a flow for fabricating a semiconductor device 1J in accordance withanother embodiment of the present disclosure.

With reference to FIG. 30 , an intermediate semiconductor device may befabricating with a procedure similar to that illustrated in FIGS. 25 to28 . The layer of first conductive material 605 may be formed to fillthe first trenches 701 and cover the first insulating layer 301.

With reference to FIG. 31 , a planarization process, such as chemicalmechanical polishing, may be performed until the top surface 101TS ofthe substrate 101 is exposed to remove excess material and provide asubstantially flat surface for subsequent processing steps. After theplanarization, the covering layers 413 may be turned into collarinsulating layers 415. The layer of first conductive material 605 may beturned into bottom portions 303B in the first trenches 701.

With reference to FIG. 32 , the inter-layer dielectric 403-1 may beformed on the substrate 101 and a connection portion 303C may be formedin the inter-layer dielectric 403-1 by a damascene process. Theconnection portion 303C and the bottom portions 303B may together form ashared conductive layer 303. The bottom conductive structure 200′″, thefirst insulating layer 301, and the shared conductive layer 303 togetherconfigure the first capacitor unit CAP1.

With reference to FIG. 33 , the second insulating layer 305, the topconductive layer 307, the inter-layer dielectric 403-3, and theconnection structure 500 may be formed with a procedure similar to thatillustrated in FIG. 15 . The shared conductive layer 303, the secondinsulating layer 305, and the top conductive layer 307 togetherconfigure the second capacitor unit CAP2. The first capacitor unit CAP1and the second capacitor unit CAP2 may be electrical parallel by theconnection structure 500.

One aspect of the present disclosure provides a semiconductor deviceincluding a substrate, a first capacitor unit, a second capacitor unit,and a connection structure. The first capacitor unit includes a bottomconductive structure inwardly positioned in the substrate, and a sharedconductive layer positioned above the bottom conductive structure with afirst insulating layer interposed therebetween. The second capacitorunit includes the shared conductive layer, a top conductive layerpositioned above the shared conductive layer with a second insulatinglayer interposed therebetween. The connection structure electricallyconnects the bottom conductive structure and the top conductive layersuch that the first capacitor unit and the second capacitor unit are inparallel.

Another aspect of the present disclosure provides a method forfabricating a semiconductor device including providing a substrate,forming a first trench in the substrate, doping sidewalls and a bottomsurface of the first trench to form a bottom conductive structure,forming a first insulating layer on the bottom conductive structure andin the first trench, forming a shared conductive layer on the firstinsulating layer, forming a second insulating layer on the sharedconductive layer, forming a top conductive layer on the secondinsulating layer, and forming a connection structure electricallyconnecting the bottom conductive structure and the top conductive layer.The bottom conductive structure, the first insulating layer, and theshared conductive layer together configure a first capacitor unit. Theshared conductive layer, the second insulating layer, and the topconductive layer together configure a second capacitor unit.

Due to the design of the semiconductor device of the present disclosure,the capacitance density may be increased by the stacked and electricallyparalleled coupled first capacitor unit CAP1 and second capacitor unitCAP2. Accordingly, the effective capacitance of the semiconductor device1A may be increased such that the performance of the semiconductordevice 1A may be improved.

It should be noted that the terms “forming,” “formed” and “form” maymean and include any method of creating, building, patterning,implanting, or depositing an element, a dopant or a material. Examplesof forming methods may include, but are not limited to, atomic layerdeposition, chemical vapor deposition, physical vapor deposition,sputtering, co-sputtering, spin coating, diffusing, depositing, growing,implantation, photolithography, dry etching and wet etching.

It should be noted that the functions or steps noted herein may occur inan order different from the order noted in the figures. For example, twofigures shown in succession may in fact be executed substantiallyconcurrently or may sometimes be executed in a reversed order, dependingupon the functionalities or steps involved.

It should be noted that, the term “about” modifying the quantity of aningredient, component, or reactant of the present disclosure refers tovariation in the numerical quantity that can occur, for example, throughtypical measuring and liquid handling procedures used for makingconcentrates or solutions. Furthermore, variation can occur frominadvertent error in measuring procedures, differences in themanufacture, source, or purity of the ingredients employed to make thecompositions or carry out the methods, and the like. In one aspect, theterm “about” means within 10% of the reported numerical value. Inanother aspect, the term “about” means within 5% of the reportednumerical value. In yet another aspect, the term “about” means within10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% of the reported numerical value.

Although the present disclosure and its advantages have been describedin detail, it should be understood that various changes, substitutionsand alterations can be made herein without departing from the spirit andscope of the disclosure as defined by the appended claims. For example,many of the processes discussed above can be implemented in differentmethodologies and replaced by other processes, or a combination thereof.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present disclosure, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present disclosure. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, and steps.

What is claimed is:
 1. A method for fabricating a semiconductor device,comprising: providing a substrate; forming a first trench in thesubstrate; doping sidewalls and a bottom surface of the first trench toform a bottom conductive structure; forming a first insulating layer onthe bottom conductive structure and in the first trench; forming firstspacers on sidewalls of the shared conductive layer; forming a sharedconductive layer on the first insulating layer and the first spacersafter forming the first spacers; forming a second insulating layer onthe shared conductive layer; forming a top conductive layer on thesecond insulating layer; and forming a connection structure electricallyconnecting the bottom conductive structure and the top conductive layer;wherein the bottom conductive structure, the first insulating layer, andthe shared conductive layer together configure a first capacitor unit,and the shared conductive layer, the second insulating layer, and thetop conductive layer together configure a second capacitor unit.
 2. Themethod for fabricating the semiconductor device of claim 1, wherein thesubstrate and the bottom conductive structure have opposite electricaltype.
 3. The method for fabricating the semiconductor device of claim 2,wherein an aspect ratio of the first trench is between about 1:6 andabout 1:20.
 4. The method for fabricating the semiconductor device ofclaim 3, wherein the first insulating layer is formed of an insulatingmaterial having a dielectric constant of about 4.0 or greater.
 5. Themethod of claim 1, wherein a width of the second insulating layer isgreater than a width of the shared conductive layer.
 6. The method ofclaim 5, wherein the connection structure comprising a first conductivevia electrically connecting the top conductive layer, a secondconductive via electrically connecting the bottom conductive structure,and a conductive line horizontally on the first conductive via and thesecond conductive via and electrically connect the first conductive viaand the second conductive via.
 7. The method of claim 6, furthercomprising: forming an assistant conductive layer between the secondconductive via and the bottom conductive structure, wherein theassistant conductive layer is formed of titanium silicide, nickelsilicide, nickel platinum silicide, tantalum silicide, or cobaltsilicide.
 8. The method of claim 7, wherein a thickness of the assistantconductive layer is between about 2 nm and about 20 nm.
 9. The method ofclaim 1, wherein the first insulating layer is an oxide-nitride-oxidestructure.
 10. The method of claim 9, further comprising: forming aninterfacial layer between the bottom conductive structure and the firstinsulating layer, wherein the interfacial layer is formed of siliconoxide.
 11. The method of claim 10, wherein a thickness of theinterfacial layer is between about 7 angstroms and about 12 angstroms.12. The method of claim 9, further comprising: forming a first barrierlayer between the first insulating layer and the shared conductivelayer, wherein the first barrier layer is formed of titanium, titaniumnitride, titanium silicon nitride, tantalum, tantalum nitride, tantalumsilicon nitride, or a combination thereof.
 13. The method of claim 12,wherein a thickness of the first barrier layer is between about 10angstroms and about 15 angstroms.
 14. The method of claim 9, wherein athickness of the first insulating layer is about 10 angstroms and about1000 angstroms.
 15. The method of claim 5, wherein a width of the topconductive layer is less than the width of the shared conductive layer.16. The method of claim 1, wherein the shared conductive layer comprisesa connection portion above a top surface of the substrate and a bottomportion extending downwardly to the substrate.